This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The storage and mobilization of lipid are fundamental cellular processes, and its dysregulation contributes to numerous diseases including diabetes, atherosclerosis and cardiomyopathy. Our central hypothesis is that regulated lipolysis involves the orderly trafficking of lipases and co-activators to specialized lipid droplet structures that are organized by specific lipid droplet scaffold proteins. We anticipate that knowledge of the specific molecular interactions that control ectopic lipid clearance will allow us to devise screens for small molecules that promote this activity, with the long term goal of identifying lead compounds for treatment of obesity-related lipotoxicity. Our lab is investigating cellular and molecular mechanisms of lipolysis in fat and muscle. We and others have shown that that mobilization of fatty acids from stored triglyceride involves specific trafficking of proteins to the droplet surface. There are direct data demonstrating the central role of PAT proteins (perilipin/ADRP/TIP47) in organizing lipolytic protein trafficking and indirect data that indicating that this occurs on specialized lipid droplets or domains of large lipid droplets. Furthermore, in addition to protein trafficking, activation of lipolysis appears to involve structural changes in the droplet surface, such as microdroplet formation. We believe that application of the 3D SEM and TEM techniques developed by NCMIR would allow unprecedented analysis if this dynamic and important organelle.